1. Field of the Invention
The present invention relates to an image processing device, an image capture device, an image processing method, and a program for a restoration process based on a point spread function.
2. Description of the Related Art
In an object image photographed through an optical system, a so-called point spread phenomenon in which a point object has minute spread due to the influence of diffraction, aberration, or the like caused by the optical system may be observed. A function representing a response of an optical system to a point light source is called a point spread function (PSF), and is known as a parameter responsible for resolution deterioration of a photographic image.
The photographic image deteriorated in image quality due to the point spread phenomenon can be recovered in image quality through a point image restoration process based on the PSF. The point image restoration process is a process in which a deterioration characteristic (point image characteristic) caused by aberration or the like of a lens is determined in advance, and point spread of the photographic image is cancelled through an image process using a restoration filter according to the point image characteristic.
The restoration filter used for the point image restoration process is designed based on various condition elements (lens type, diaphragm value (F value), zoom magnification, object distance, image height, and the like) which may affect the PSF of the optical system. When the number of types of the condition elements of the restoration filter increases, a strict point image restoration process becomes possible; however, the amount of data of the restoration filter is enlarged, and the storage capacity required for storing the restoration filter becomes excessive. Furthermore, advanced arithmetic processing performance is required for a filtering process (deconvolution operation) of the point image restoration process, and in particular, the importance of simplification and acceleration of the point image restoration process is increasing along with an increase in the number of pixels of image data in recent years.
In regard to the restoration process based on the PSF, for example, JP2010-141661A discloses an image processing device which scales an image trimmed by the magnification of a digital zoom according to a designated size, and performs a restoration process for the scaled image. Furthermore, JP2011-10214A discloses an image processing control method which applies a recovery filter to an image photographed by a camera capable of photographing a moving image and a still image to reduce image deterioration, such as blurring.